To be honest with you, I don't do it via any controlled way that allows me to say if I don't do this, this will happen... Except if I change any of this routine, the wendtii makes like a snowman in the middle of summer. All I can say is that what I grow does well. (C. helferi, B. aubertii, B. japonica, R. indica, E. triandra, H. micranthemoides, M. umbrusom, A. nana, A. nana petite, C. wendtii, B. caroliniana, M. mattagrossense, H. palustris, Lobelia). I have some issues with A. reinickii and curling leaves which I think I am correcting by adding Mg. BUT I CAN'T GROW LUDWIGIAS WORTH A DAMN!!
No matter which Lud I try, it will eventually die.
These numbers are a combination of advice and looking at what others do/have done:
50 gal tank with 126W lighting: Flourish: 2.5ml; Flourish iron 1ml
29 gal tank with 75W lighting: Flourish: 2ml; Flourish iron: 0.75ml
10 gal tanks with 26W lighting: Flourish: .75ml; Flourish iron: 0.25ml
They are added daily except on the day I do the water changes when I dose the macros.